Extracts of Tanacetum parthenium, a plant belonging to the family Asteracee/Composite, also known as Altamisa, Crisanthemum, Leucanthemum, Pyrethrum parthenium as well as under the common name "feverfew", have traditionally been used in the treatment of migraine, vertigo, arthritis, menstrual disorders, fever, toothache, stomach ache and insect bites. Extracts of Tanacetum parthenium contain various volatile oils having mono- and/or sesquiterpene components, flavonoids, tannins, and pyrethrin, as well as terpenoids of the family of sesquiterpene lactones known as germacranolides, guaianolides and eudesmanolides. These latter compounds are characterized by an .alpha.-unsaturated .gamma.-lactone structure and comprise in particular the compounds known as parthenolide, 3-.beta.-hydroxy-parthenoide, costunolide, 3-.beta.-hydroxy-costunolide, artemorin, 8-.alpha.-hydroxy-estafiatin and chrysanthemonin. The presence of these sesquiterpene lactones is considered necessary for the extracts to achieve pharmacological activity (J. Pharm. Pharmacol. 1992, 44:391-395).
Particular attention has been focused on parthenolide, which is thought to be the fundamental active ingredient of these extracts, but which is also responsible for allergic reactions which can sometimes occur following treatment with the extracts of Tanacetum parthenium (See, for example, Arch. Dermatol. Forsch. 1975, 251 (3):235-44; Arch. Dermatol. Forsch. 1976, 255 (2):111-21; Contact Dermatitis, 1988, 38 (4):207-8; Am. J. Contact Dermatol. 1998-9 (1):49-50; Br. J. Dermatol. 1995, 132 (4):543-7). Extracts of Tanacetum parthenium containing parthenolide are disclosed in WO 94 06800; EP 0 553 658; WO 92 11857; GB 2,166,952; EP 98 041; WO 98 39018.